This chapter emphasized a comparison between biodiesel, green diesel and petrol diesel. In general, diesel is referred to any liquid fuel specifically designed for the automotive engine as a fuel. Generally, biodiesel is an alternative fuel that has similar properties to conventional diesel fuel. Biodiesel can be produced from vegetable oils, animal fats or waste cooking oil via catalysed transesterification process. Biodiesel is renewable energy, nontoxic and biodegradable and may reduce net carbon monoxide emission by 78% compared to petrol diesel. Green diesel is one of the alternative fuels which has a similar molecule structure as petrol diesel and yet it provides better diesel properties in terms of higher heating value, energy density, very high cetane numbers and outstanding cold flow properties compared to conventional biodiesel. Green diesel is produced by hydrotreating triglycerides in vegetable oils with hydrogen. The most common type of diesel fuel is petrol diesel. It is produced from the fractional distillation of crude petroleum between the temperature of 200 and 350 °C at atmospheric pressure resulting in a mixture of carbon chains that typically contain between 8 and 21 carbon atoms per molecule.